1. Technical Field
The present invention relates to rotating electric machines that are used in, for example, motor vehicles as electric motors and electric generators.
2. Description of Related Art
There are known rotating electric machines which include a rotor and a state. The stator includes an annular stator core and a three-phase stator coil. The stator core is disposed radially outside the rotor so as to surround the rotor. Moreover, the state core has a plurality of slots arranged in its circumferential direction. The state coil is comprised of a plurality of phase windings. The phase windings are mounted on the stator core so as to be partially received in the slots of the stator core. In addition, those parts of the phase windings which are located outside the slots of the stator core together make up a pair of coil ends of the stator coil which respectively protrude from an opposite pair of axial end faces of the stator core.
In operation, electric current flows in the stator coil, causing the stator coil to generate heat. Therefore, to prevent a decrease in efficiency of the rotating electric machine due to the heat generated by the stator coil, it is necessary to suitably cool the stator coil. To this end, cooling air may be supplied to flow through the stator and the rotor. Alternatively, as disclosed in Japanese Patent Application Publication No. JP2010011623A, cooling liquid may be supplied to the coil ends of the stator coil from the upside of the coil ends.
Moreover, the phase windings of the stator coil are generally star-connected to define a neutral point therebetween. Consistently, when electric current flows in the stator coil, it is easiest for the temperature of the stator coil to become high in the vicinity of the neutral point. Accordingly, it is desired to improve the cooling performance of the stator coil in the vicinity of the neutral point.